Power cable useful in seismic testing

Abstract

A self-supporting power cable which is especially useful in seismic testing. The cable includes an outer armor layer, a pair of tensile elements located inside the armor layer, a power conveying assembly located inside the armor layer and between the tensile elements, and filler material filling the otherwise empty spaces within the armor layer. The tensile elements are advantageously formed of several concentric layers of spirally-wrapped wire strands with at least the outer layer having less than a full contingent of strands. This improves the cable's strength-to-weight ratio while providing self support. To provide transverse force resistance against the cleats of a feeding device, the outer layer of the wire ropes contact the walls of the outer armor layer.

What is claimed is: 
     
       1. A power cable, the combination comprising: an outer armor layer having a longitudinal axis Z, orthogonal transverse axes X and Y, and a cavity defined therein having a height in the Y direction of A;   a pair of tensile elements located in said cavity, extending along said Z axis, and spaced apart along said X axis, each of said tensile elements including an inner tensile member, and   an outer tensile member, said outer tensile member including one pair of strands spirally wrapped about said inner tensile member, said strands in said pair being circumferentially spaced from one another through substantially 180°,   said outer tensile member having circumferential gaps therein between said strands, and said strands having outer edges separated by a distance substantially equal to A;     power conveying means located in said cavity, extending along said Z axis, and positioned between said pair of tensile elements; and   filler material located in said cavity and substantially filling any otherwise empty spaces therein,   said outer armor layer having a top wall in contact with the outer edges of said strands in each of said outer tensile members, and a bottom wall in contact with the outer edges of said strands in each of said outer tensile members, said top and bottom walls extending transversely of said cavity along the X axis.   
     
     
       2. A power cable according to claim 1, wherein said outer armor layer is metallic.   
     
     
       3. A power cable according to claim 1, wherein said outer armor layer is formed as a spiral wrapping.   
     
     
       4. A power cable according to claim 1, wherein said outer armor layer top and bottom walls are substantially straight and parallel, said outer armor layer further including concave left and right side walls extending in the Y direction.   
     
     
       5. A power cable according to claim 1, wherein said outer armor layer has a left side wall in contact with the outer edges of said strands in one of said tensile elements, and a right side wall in contact with the outer edges of said strands in the other of said tensile elements.   
     
     
       6. A power cable according to claim 1, wherein each of said inner tensile members includes a spirally-formed wire rope.   
     
     
       7. A power cable according to claim 6, wherein each of said spirally-formed wire ropes includes a plurality of inner strands having circumferential gaps therebetween.   
     
     
       8. A power cable according to claim 6, wherein each of said spirally-formed wire ropes includes a central strand,   a continuous set of inner strands spirally wrapped about said central strand, and   a set of intermediate inner strands spirally wrapped about said continuous set and having circumferential gaps therebetween.     
     
     
       9. A power cable according to claim 6, wherein said outer tensile member further includes additional pairs of strands spirally wrapped about said inner tensile member, said strands in each of said additional pairs being circumferentially spaced from one another through substantially 180°,   said strands in said additional pairs having outer edges separated by a distance substantially equal to A.   
     
     
       10. A power cable according to claim 1, wherein said outer tensile member further includes a second pair of strands spirally wrapped about said inner tensile member, said strands in said second pair being circumferentially spaced from one another through substantially 180°,   said strands in said second pair having outer edges separated by a distance substantially equal to A,   one of the strands in said pair being adjacent one of the strands in said second pair, and the other of the strands in said pair being adjacent the other of the strands in said second pair.   
     
     
       11. A power cable according to claim 1, wherein each of said strands comprises a solid wire.   
     
     
       12. A power cable according to claim 1, wherein said power conveying means comprises an inner armor layer.   
     
     
       13. A power cable according to claim 12, wherein said inner armor layer is formed as a metallic, spiral wrapping.   
     
     
       14. A power cable according to claim 12, wherein said inner armor layer contacts said pair of tensile elements.   
     
     
       15. A power cable according to claim 1, wherein each of said tensile elements is substantially rigid in the X and Y directions.   
     
     
       16. A power cable, the combination comprising: an outer armor layer having a longitudinal axis Z, orthogonal transverse axes X and Y, and a cavity defined therein having a height in the Y direction of A;   a pair of tensile elements located in said cavity, extending along said Z axis, and spaced apart along said X axis, each of said tensile elements including an inner wire rope, and   an outer wire rope, said outer wire rope including one pair of strands spirally wrapped about said inner wire rope, said strands in said pair being circumferentially spaced from one another through substantially 180°,   said outer wire rope having circumferential gaps therein between said strands, and said strands having outer edges separated by a distance substantially equal to A and contacting said outer armor layer;     power conveying means located in said cavity, extending along said Z axis, and positioned between said pair of tensile elements; and   filler material located in said cavity and substantially filling any otherwise empty spaces therein,   said outer armor layer having a top wall in contact with the outer edges of said strands in each of said outer wire ropes, and a bottom wall in contact with the outer edges of said strands in each of said outer wire ropes, said top and bottom walls extending transversely of said cavity along the X axis.   
     
     
       17. A power cable according to claim 16, wherein said outer armor layer has a left side wall in contact with the outer edges of said strands in one of said tensile elements, and a right side wall in contact with the outer edges of said strands in the other of said tensile elements.